MONROVIA/CONAKRY (Reuters) - West African nations scrambled
on Tuesday to contain an outbreak of the deadly Ebola virus
suspected to have killed at least 59 in Guinea, with people
presenting symptoms of the disease reported in neighboring
Sierra Leone and Liberia.

Health authorities in Liberia said five out of six people
who crossed the border from Guinea to seek treatment and showed
symptoms of the fever had died.

Liberia's Chief Medical Officer Bernice Dahn said it was not
confirmed if the cases were Ebola, one of the most lethal
infectious diseases known to humans, and tests were being
carried out.

The World Health Organization (WHO) said a total of 86
suspected cases, including 59 deaths, had been reported in
southeastern Guinea near the border with Sierra Leone and
Liberia. Laboratory tests have confirmed 13 cases of Ebola in
Guinea so far, the first outbreak of the disease in West Africa.

"The patients we have seen thus far have similar symptoms to
those of the people in Guinea," Dahn said. "Those people had the
sickness and crossed over into Liberia's Lofa county for
treatment. Five died."

Samples taken from those who died in Liberia had been sent
to Conakry for testing, according to the Geneva-based WHO.

In Guinea, authorities have taken steps to quarantine
suspected cases in the districts of Guekedou, Macenta, Nzerekore
and Kissidougou.

VIRULENT STRAIN

In neighboring Sierra Leone, authorities set up a taskforce
after the death of a 14-year-old boy who had attended the
funeral of a suspected Ebola victim. Authorities are yet to
confirm if the boy died of the disease.

Sierra Leone was receiving help from the WHO and the U.S.
firm Metabiota, which investigates infectious disease threats,
said Chief Medical Officer Brima Kargbo.

Initial reports indicated a Canadian who showed Ebola-like
symptoms after traveling to West Africa had tested negative for
the virus, WHO spokesman Tarik Jasarevic told reporters.

Ebola was discovered in 1976 in then-Zaire, now Democratic
Republic of Congo. Scientists have identified the outbreak in
Guinea as the virulent Zaire strain of the virus.

Because people who fall sick with it tend to vomit, have
diarrhea and suffer both internal and external bleeding, their
bodies are often "covered in virus," explained Peter Piot, one
of the co-discoverers of Ebola and now director of the London
School of Hygiene and Tropical Medicine.

This means anyone in close contact with them - such as
nurses, doctors and carers - is at risk, he said.

Esther Sterk, a tropical diseases specialist at the
international medical charity Medecins Sans Frontieres, said
after an incubation period of between 2 and 21 days, the virus
causes a raging fever, headaches, muscle pain, conjunctivitis
and weakness, before moving into more severe phases of causing
vomiting, diarrhea and hemorrhages.

"Patients may have heavy bleeding, including from the nose
or via their urine," she said in a briefing note on the disease.

She added, however, that while dangerous, Ebola remains
rare. Since the virus was discovered in 1976, around 2,200 cases
have been recorded. Of those, 1,500 were fatal.

The last major outbreak of the Zaire strain was in 2007,
when 187 people died in Congo, a fatality rate of 74 percent.

Scientists are not clear how the virus - which also infects
animals including bats, believed to be a major reservoir of the
disease - crossed the continent from Sudan, Congo and Uganda.

With ethnic and family ties and trade making cross-border
travel common in the region, the outbreak in Guinea is causing
concern in nearby West African nations.

Mali said it was working with the WHO to put in place
preventive measures, including stronger border control health
checks, and a mechanism for coping with potential victims.

The WHO's Jasarevic said the main areas authorities should
focus on were infection control, scaling up laboratory testing
facilities and ensuring the best clinical management of
confirmed cases of infection.

"It's also about working with health workers so they know
how to treat patients properly so they don't fall victim
themselves," he said.